Sodium-ion battery and electric apparatus containing same

Abstract

This application relates to a sodium-ion battery and an electric apparatus containing the same. The sodium-ion battery includes a positive electrode plate, a separator, and a negative electrode current collector. The separator is disposed between the positive electrode plate and the negative electrode current collector. A coating is provided on a surface of the negative electrode current collector, the coating includes a carbon material, and the carbon material includes carbon nanotubes. The sodium-ion battery can effectively enhance the suppression of sodium dendrites and improve the cycling performance. In addition, it is unnecessary to additionally provide a negative electrode active material layer, reducing the costs of the sodium-ion battery and improving the energy density of the sodium-ion battery.

What is claimed is: 
     
         1 . A sodium-ion battery, comprising a positive electrode plate, a separator, and a negative electrode current collector, wherein the separator is disposed between the positive electrode plate and the negative electrode current collector, a coating is provided on a surface of the negative electrode current collector, the coating comprises a carbon material, and the carbon material comprises carbon nanotubes. 
     
     
         2 . The sodium-ion battery according to  claim 1 , characterized in that the carbon nanotube has at least one of the following characteristics:
 (1) a specific surface area is greater than or equal to 500 m 2 /g, optionally, the specific surface area of the carbon nanotube is 500-1500 m 2 /g, and further optionally, the specific surface area of the carbon nanotube is 750-1000 m 2 /g; and   (2) a tube diameter is 0.5-50 nm, and optionally, the tube diameter is 10-40 nm.   
     
     
         3 . The sodium-ion battery according to  claim 1 , characterized in that a number of metal nanoparticles are attached to the carbon nanotube. 
     
     
         4 . The sodium-ion battery according to  claim 3 , characterized in that the metal nanoparticle has at least one of the following characteristics:
 (1) a metal in the metal nanoparticle is a metal capable of forming an alloy with sodium, and optionally, the metal nanoparticle comprises one or more of Au nanoparticle, Ag nanoparticle, Bi nanoparticle, Sn nanoparticle, Co nanoparticle, Ni nanoparticle, Mg nanoparticle, and Zn nanoparticle;   (2) particle size of the metal nanoparticle is at least 0.2 nm smaller than the tube diameter of the carbon nanotube, optionally, the particle size of the metal nanoparticle is 0.2-10 nm smaller than the tube diameter of the carbon nanotube, and further optionally, the particle size of the metal nanoparticle is 1-5 nm smaller than the tube diameter of the carbon nanotube; and   (3) the particle size of the metal nanoparticle is 0.3-40 nm, and optionally, the particle size of the metal nanoparticle is 8-35 nm.   
     
     
         5 . The sodium-ion battery according to  claim 3 , characterized in that in the coating, mass of the metal nanoparticle is M1, and mass of the carbon nanotube is M2, wherein M1:M2=0.01-0.1, and optionally, M1:M2=0.03-0.07. 
     
     
         6 . The sodium-ion battery according to  claim 1 , characterized in that thickness of the coating is 0.5-15 μm, and optionally, the thickness of the coating is 0.5-5 μm. 
     
     
         7 . The sodium-ion battery according to  claim 1 , characterized in that a material of the coating further comprises a binder, optionally, the binder comprises a polymer binder, and further optionally, the binder comprises one or more of styrene-butadiene rubber, polyacrylic acid, polyacrylic acid sodium, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, and carboxymethyl chitosan. 
     
     
         8 . The sodium-ion battery according to  claim 1 , characterized in that the sodium-ion battery further comprises an electrolyte. 
     
     
         9 . The sodium-ion battery according to  claim 8 , characterized in that the electrolyte has at least one of the following characteristics:
 (1) a solvent in the electrolyte comprises an ether solvent, and optionally, the solvent in the electrolyte comprises one or more of dimethoxyethane, diethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofurann, diphenyl ether, and crown ether;   (2) an electrolytic sodium salt in the electrolyte comprises one or more of sodium hexafluorophosphate, sodium difluoroxalate borate, sodium tetrafluoroborate, sodium bisoxaloborate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethanesulfonate, and sodium bis(trifluoromethanesulfonyl)imide; and   (3) the electrolytic sodium salt in the electrolyte has a molar concentration of 0.5 mol/L to 8 mol/L, and optionally, the electrolytic sodium salt in the electrolyte has a molar concentration of 1 mol/L to 4 mol/L.   
     
     
         10 . The sodium-ion battery according to  claim 1 , characterized in that a sodium metal layer is formed on at least one of an inner wall of the carbon nanotube, an outer wall of the carbon nanotube, and the surface of the negative electrode current collector. 
     
     
         11 . The sodium-ion battery according to  claim 10 , characterized in that the sodium metal layer is formed in a charge and discharge process of the sodium-ion battery, and optionally, the charge and discharge process comprises a charge and discharge process during formation. 
     
     
         12 . The sodium-ion battery according to  claim 10 , characterized in that thickness of the sodium metal layer is P, and 0<P≤400 nm. 
     
     
         13 . A preparation method of sodium-ion battery, comprising the following steps:
 mixing a material of a coating with a solvent to prepare a slurry, wherein the material of the coating comprises a carbon material, and the carbon material comprises carbon nanotubes;   applying the slurry on a surface of a negative electrode current collector, followed by drying, to form a coating; and   laminating the negative electrode current collector with the coating, a separator, and a positive electrode plate.   
     
     
         14 . The preparation method of sodium-ion battery according to  claim 13 , characterized in that the sodium-ion battery is subjected to at least one charge and discharge process, a sodium metal layer is formed on at least one of an inner wall of the carbon nanotube, an outer wall of the carbon nanotube, and the surface of the negative electrode current collector, and optionally, the charge and discharge process comprises a charge and discharge process during formation. 
     
     
         15 . An electric apparatus, characterized by comprising the sodium-ion battery according to  claim 1 .